>today it is working , tommorow it could be stop?
Software does not spontaneously break.

>Documentation should get answer.
Documentation is never 100% correct.

Trust, but VERIFY with own testing.

Unfortunately, verification is not what the OP is after. He wants to know if his assumptions can be FALSIFIED. Therefor his question is very valid, since depending on data, a piece of code that seems to be working fine, might (from the look of it) "suddenly go awry".